BASIL/NIDUS Harmonization Paper
Doug Tommet, Rich Jones
2018-03-07
Goal
The goal of this paper is to describe the level of agreement and a harmonized scale of severity applicable to several commonly used delirium instruments: the CAM-S, DRS-R-98, MDAS. We do this in the context of a single clinical research study, where a team of trained lay interviewers administered each instrument along with supporting stimulus assessments in the same group of patients.
Note: In writing the paper, use the term “features” instead of “signs/symptoms”.
Summary of Results
IRT Models (dichotomous outcomes) estimated for all three instruments: CAM-S, DRS-R-98, MDAS
The instrument item responses were dichotomized into “none” vs “any” symptom.
The model fit to 8 core items per instrument is good. The core items include Sleep disturbance, Perceptual disturbance, Psychomotor agitation/retardation, Orientation, Attention, Memory impairment, and Disorganized Thinking.
Initially the fit to the expanded item sets was unacceptably bad. Then we recoded the sleep disturbance item, combining the “none” and “mild” categories. The model fit was then acceptable.
Item Parameters have been co-calibrated
The MDAS and CAM-S items have been equated to the DRS-R-98.
The items used to link the MDAS to the DRS-R-98 are: Disorientation, Perceptual disturbance, Sleep/wake cycle disturbance, Short term memory impairment, Delusions, and Disorganized Thinking.
The items used to link the CAM-S to the DRS-R-98 are: Disorientation, Perceptual disturbance, Sleep/wake cycle disturbance, Psychomotor agitation, Psychomotor retardation, Attention and Disorganized Thinking.
Created item response theory plots for the dichotomous outcome models
Created plots for: Test Information function, Item characteristic curves, Test characteristic curves, and density plots of estimated latent scores.
Estimated thresholds for polytomous outcomes for all three instruments: CAM-S, DRS-R-98, MDAS
Used the equated item parameters from the previous step to estimate the thresholds for the polytomous outcomes.
Note: Some thresholds are missing for some items since the highest categories weren’t observed.
Created model for the CAM-S short form
Took the four items from the CAM-S item parameters estimated for the polytomous outcomes.
Created item response theory plots for the polytomous outcome models
Created plots for: Test Information function, Item characteristic curves, Test characteristic curves, and density plots of estimated latent scores.
Created the proposed tables/figures for the manuscript
The tables are the typical Table 1 and a table of model fit statistics. The figures include a plot showing the item thresholds, a test information curve, a scatter plot of the factor scores for the four instruments, and a test characteristic curve that can create a crosswalk between instruments.
Created nomograms crosswalk tables and figures for the appendix
I prefer the tables over the figures because there are only four tables but twelve figures.
Examined the difference in information provided using polytomous versus dichotomous outcomes
We were interested in whether we could use the items as dichotomous outcomes in the new instrument since it would make training to use the instrument easier. However, the higher category outcomes provide a lot of information at higher “Delirium Intensity” levels. We felt this would be needed for a severity instrument.
Update 1-8-2018: Test reliability
Added measures of test reliability. In the descriptive statistics section of the report, added item correlations and Cronbach’s alpha. In the model fitting section of the report, added McDonald’s omega.
Update 1-24-2018: “Level of consciousness” recoding
The handling of the item CAM-S 4 “Altered level of consciousness” in the polytomous model was wrong. The initial recoding of the item was correct. The response categories “Stupor” and “Coma” were recoded as “Lethargic”, but since there weren’t any responses in those categories, there was nothing to recode. The responses for this item are nominal (“Normal”, “Vigilant”, “Lethargic”) so it’s wrong to treat it as ordered categories in the CFA model.
There are several options were considered to fix the coding. One is to collapse the response categories so that it becomes “Normal” vs “Abnormal / Everything else”. Another is, since there are few “Vigilant” responses, to recode these to missing or “Normal” and the item becomes “Normal” vs “Lethargic”. Another way is to turn the item into two indicators: “Normal” vs “Vigilant” and “Normal” vs “Lethargic”.
Turning the item into two indicators is the approach used in this report. This approach retains all the information provided in the item.
Update 1-29-2017: Figure aesthitics
Figure 1: Removed the item number from the left hand column. Added an solid line above the rugplot. Labeled the rugplot. Created a new version of the figure, removing the left hand column and putting it into a legend.
Figure 2: Added a rugplot to the Information and Reliability plots
Figure 3: Made the dots smaller and more transparent
Figure 4: Added a rugplot to the test characteristic curve plot
Report
Data Processing
Read Data
The data comes from /BASIL/POSTED/DATA/DERIVED/clean/current/. On 9-17-2017, the data was copied to the folder /BASIL/Projects/DeliriumHarmonization/POSTED/DATA/DERIVED/clean/current/ to make the results reproducible.
The file has 352 subjects and 1190 interviews.
This analysis will only use baseline hospital visits and daily hospital visits. Interviews that are not complete are dropped. Interviews that are missing the CAM-S vds, the DRS vds, or the MDAS vds are dropped. There are three subjects that de-enrolled from the study and are dropped from the analysis. [11-9-2017 decision: Do not exclude these three subjecs.] After applying these filters there are 352 subjects and 1178 interviews remaining in the datafile.
Data recode
The items that were coded as Don’t Know, Refused, Uncertain were set to missing, and the response options were reordered such that no symptoms were 0 and any symptoms were positive values.
The DRS, MDAS, CAM-S items are dichotomized to None vs Any symptom.
It is always possible once the item parameters are calibrated in the dichotomous setting to go back to the polytomous response setting. However, there should be at least 5% in the response categories and that is not always the case. So, we may end up in a situation where some items are dichotomous and others are polytomous. This makes the interpretation more difficult.
Item reference table
This table is a reference for the following tables to link item numbers to item content
DRS
| Item | Content |
|---|---|
| rdrs01 | Sleep-wake cycle disturbance |
| rdrs02 | Perceptual disturbances and hallucinations |
| rdrs03 | Delusions |
| rdrs04 | Lability of affect |
| rdrs05 | Language |
| rdrs06 | Thought process abnormalities |
| rdrs07 | Motor agitation |
| rdrs08 | Motor retardation |
| rdrs09 | Orientation |
| rdrs10 | Attention |
| rdrs11 | Short-term memory |
| rdrs12 | Long-term memory |
| rdrs13 | Visuospatial ability |
MDAS
| Item | Content |
|---|---|
| rmdas01 | Reduced level of consciousness (Awareness) |
| rmdas02 | Disorientation |
| rmdas03 | Short-term memory impairment |
| rmdas04 | Impaired digit span |
| rmdas05 | Reduced ability to maintain and shift attention |
| rmdas06 | Disorganized thinking |
| rmdas07 | Perceptual disturbance |
| rmdas08 | Delusions |
| rmdas09 | Decreased or increased psychomotor activity |
| rmdas10 | Sleep-wake cycle disturbance |
CAM-S
| Item | Content |
|---|---|
| rcamlf1a | Acute change |
| rcamlf2a | Inattention |
| rcamlf3a | Disorganized thinking |
| rcamlf4l | Altered level of consciousness (Lethargic) |
| rcamlf4v | Altered level of consciousness (Vigilant) |
| rcamlf5a | Disorientation |
| rcamlf6a | Memory impairment |
| rcamlf7a | Perceptual disturbances |
| rcamlf8a | Psychomotor agitation |
| rcamlf8d | Psychomotor retardation |
| rcamlf9a | Sleep-wake cycle disturbance |
Descriptive statistics
Summary tables/statistics for DRS (N=1178)
Original item category frequencies (%)
| Item | 0 | 1 | 2 | 3 | Missing |
|---|---|---|---|---|---|
| rdrs04 | 97.62 | 1.70 | 0.59 | 0.00 | 0.08 |
| rdrs08 | 97.62 | 1.78 | 0.59 | 0.00 | 0.00 |
| rdrs07 | 97.03 | 2.29 | 0.51 | 0.00 | 0.17 |
| rdrs03 | 94.99 | 2.55 | 0.68 | 1.02 | 0.76 |
| rdrs05 | 86.93 | 11.46 | 1.10 | 0.34 | 0.17 |
| rdrs13 | 86.76 | 9.76 | 1.87 | 0.08 | 1.53 |
| rdrs06 | 86.16 | 8.57 | 4.67 | 0.42 | 0.17 |
| rdrs02 | 84.13 | 4.58 | 3.90 | 6.62 | 0.76 |
| rdrs09 | 75.13 | 14.43 | 9.51 | 0.42 | 0.51 |
| rdrs11 | 52.29 | 25.30 | 7.56 | 14.18 | 0.68 |
| rdrs12 | 45.50 | 23.60 | 11.46 | 17.74 | 1.70 |
| rdrs10 | 43.12 | 43.04 | 12.99 | 0.76 | 0.08 |
| rdrs01 | 25.64 | 67.66 | 6.03 | 0.34 | 0.34 |
Dichotomized item category frequencies (%)
| Item | 0 | 1 | Missing |
|---|---|---|---|
| rdrs04 | 97.62 | 2.29 | 0.08 |
| rdrs08 | 97.62 | 2.38 | 0.00 |
| rdrs07 | 97.03 | 2.80 | 0.17 |
| rdrs03 | 94.99 | 4.24 | 0.76 |
| rdrs01 | 93.29 | 6.37 | 0.34 |
| rdrs05 | 86.93 | 12.90 | 0.17 |
| rdrs13 | 86.76 | 11.71 | 1.53 |
| rdrs06 | 86.16 | 13.67 | 0.17 |
| rdrs02 | 84.13 | 15.11 | 0.76 |
| rdrs09 | 75.13 | 24.36 | 0.51 |
| rdrs11 | 52.29 | 47.03 | 0.68 |
| rdrs12 | 45.50 | 52.80 | 1.70 |
| rdrs10 | 43.12 | 56.79 | 0.08 |
Item correlations
| rdrs01 | rdrs02 | rdrs03 | rdrs04 | rdrs05 | rdrs06 | rdrs07 | rdrs08 | rdrs09 | rdrs10 | rdrs11 | rdrs12 | rdrs13 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| rdrs01 | NA | 0.11 | 0.05 | 0.15 | 0.18 | 0.17 | 0.08 | 0.16 | 0.12 | 0.09 | 0.11 | 0.10 | 0.06 |
| rdrs02 | 0.11 | NA | 0.22 | 0.16 | 0.11 | 0.37 | 0.13 | 0.03 | 0.17 | 0.23 | 0.09 | 0.06 | 0.16 |
| rdrs03 | 0.05 | 0.22 | NA | 0.24 | 0.12 | 0.36 | 0.13 | 0.03 | 0.11 | 0.13 | 0.07 | 0.09 | 0.10 |
| rdrs04 | 0.15 | 0.16 | 0.24 | NA | 0.11 | 0.22 | 0.29 | 0.13 | 0.08 | 0.08 | 0.05 | 0.04 | 0.03 |
| rdrs05 | 0.18 | 0.11 | 0.12 | 0.11 | NA | 0.34 | 0.23 | 0.09 | 0.23 | 0.22 | 0.25 | 0.25 | 0.24 |
| rdrs06 | 0.17 | 0.37 | 0.36 | 0.22 | 0.34 | NA | 0.22 | 0.10 | 0.37 | 0.31 | 0.24 | 0.23 | 0.31 |
| rdrs07 | 0.08 | 0.13 | 0.13 | 0.29 | 0.23 | 0.22 | NA | 0.04 | 0.13 | 0.12 | 0.11 | 0.10 | 0.19 |
| rdrs08 | 0.16 | 0.03 | 0.03 | 0.13 | 0.09 | 0.10 | 0.04 | NA | 0.16 | 0.09 | 0.07 | 0.06 | 0.07 |
| rdrs09 | 0.12 | 0.17 | 0.11 | 0.08 | 0.23 | 0.37 | 0.13 | 0.16 | NA | 0.33 | 0.31 | 0.32 | 0.16 |
| rdrs10 | 0.09 | 0.23 | 0.13 | 0.08 | 0.22 | 0.31 | 0.12 | 0.09 | 0.33 | NA | 0.37 | 0.37 | 0.22 |
| rdrs11 | 0.11 | 0.09 | 0.07 | 0.05 | 0.25 | 0.24 | 0.11 | 0.07 | 0.31 | 0.37 | NA | 0.84 | 0.28 |
| rdrs12 | 0.10 | 0.06 | 0.09 | 0.04 | 0.25 | 0.23 | 0.10 | 0.06 | 0.32 | 0.37 | 0.84 | NA | 0.29 |
| rdrs13 | 0.06 | 0.16 | 0.10 | 0.03 | 0.24 | 0.31 | 0.19 | 0.07 | 0.16 | 0.22 | 0.28 | 0.29 | NA |
Item - total score correlation
Correlation between the item and the sum of the dichotomous items.
| total score | |
|---|---|
| rdrs01 | 0.31 |
| rdrs02 | 0.42 |
| rdrs03 | 0.33 |
| rdrs04 | 0.24 |
| rdrs05 | 0.51 |
| rdrs06 | 0.63 |
| rdrs07 | 0.31 |
| rdrs08 | 0.22 |
| rdrs09 | 0.59 |
| rdrs10 | 0.64 |
| rdrs11 | 0.72 |
| rdrs12 | 0.71 |
| rdrs13 | 0.50 |
Cronbach’s alpha
##
## Reliability analysis
## Call: psych::alpha(x = .)
##
## raw_alpha std.alpha G6(smc) average_r S/N ase mean sd
## 0.75 0.73 0.76 0.17 2.7 0.0097 0.2 0.17
##
## lower alpha upper 95% confidence boundaries
## 0.73 0.75 0.77
##
## Reliability if an item is dropped:
## raw_alpha std.alpha G6(smc) average_r S/N alpha se
## rdrs01 0.75 0.73 0.76 0.19 2.7 0.0098
## rdrs02 0.74 0.72 0.75 0.18 2.6 0.0097
## rdrs03 0.74 0.73 0.76 0.18 2.7 0.0099
## rdrs04 0.75 0.73 0.76 0.18 2.7 0.0098
## rdrs05 0.73 0.71 0.74 0.17 2.5 0.0103
## rdrs06 0.71 0.69 0.72 0.16 2.2 0.0108
## rdrs07 0.74 0.73 0.75 0.18 2.6 0.0099
## rdrs08 0.75 0.74 0.77 0.19 2.8 0.0098
## rdrs09 0.72 0.71 0.74 0.17 2.4 0.0106
## rdrs10 0.72 0.71 0.74 0.17 2.4 0.0109
## rdrs11 0.70 0.70 0.71 0.16 2.4 0.0117
## rdrs12 0.70 0.70 0.71 0.16 2.4 0.0116
## rdrs13 0.73 0.72 0.75 0.17 2.5 0.0103
##
## Item statistics
## n raw.r std.r r.cor r.drop mean sd
## rdrs01 1174 0.32 0.38 0.27 0.21 0.064 0.24
## rdrs02 1169 0.43 0.44 0.35 0.28 0.152 0.36
## rdrs03 1169 0.33 0.41 0.32 0.24 0.043 0.20
## rdrs04 1177 0.29 0.40 0.30 0.20 0.023 0.15
## rdrs05 1176 0.52 0.53 0.46 0.39 0.129 0.34
## rdrs06 1176 0.64 0.66 0.65 0.53 0.137 0.34
## rdrs07 1176 0.34 0.43 0.34 0.25 0.028 0.17
## rdrs08 1178 0.23 0.32 0.20 0.16 0.024 0.15
## rdrs09 1172 0.59 0.55 0.49 0.44 0.245 0.43
## rdrs10 1177 0.63 0.56 0.51 0.48 0.568 0.50
## rdrs11 1170 0.72 0.60 0.63 0.57 0.474 0.50
## rdrs12 1158 0.71 0.59 0.62 0.56 0.537 0.50
## rdrs13 1160 0.50 0.48 0.41 0.37 0.119 0.32
##
## Non missing response frequency for each item
## 0 1 miss
## rdrs01 0.94 0.06 0.00
## rdrs02 0.85 0.15 0.01
## rdrs03 0.96 0.04 0.01
## rdrs04 0.98 0.02 0.00
## rdrs05 0.87 0.13 0.00
## rdrs06 0.86 0.14 0.00
## rdrs07 0.97 0.03 0.00
## rdrs08 0.98 0.02 0.00
## rdrs09 0.76 0.24 0.01
## rdrs10 0.43 0.57 0.00
## rdrs11 0.53 0.47 0.01
## rdrs12 0.46 0.54 0.02
## rdrs13 0.88 0.12 0.02Summary tables/statistics for MDAS (N=1178)
Original item category frequencies (%)
| Item | 0 | 1 | 2 | 3 | Missing |
|---|---|---|---|---|---|
| rmdas08 | 94.91 | 3.23 | 1.10 | 0.08 | 0.68 |
| rmdas09 | 94.91 | 3.74 | 1.27 | 0.00 | 0.08 |
| rmdas01 | 94.57 | 4.16 | 1.19 | 0.00 | 0.08 |
| rmdas06 | 84.55 | 10.70 | 4.16 | 0.59 | 0.00 |
| rmdas07 | 84.21 | 12.82 | 2.21 | 0.08 | 0.68 |
| rmdas02 | 76.40 | 14.18 | 5.69 | 3.14 | 0.59 |
| rmdas05 | 58.74 | 29.20 | 11.12 | 0.93 | 0.00 |
| rmdas03 | 51.19 | 23.68 | 18.76 | 5.69 | 0.68 |
| rmdas04 | 29.20 | 57.22 | 12.56 | 0.59 | 0.42 |
| rmdas10 | 25.47 | 68.85 | 5.01 | 0.34 | 0.34 |
Dichotomized item category frequencies (%)
| Item | 0 | 1 | Missing |
|---|---|---|---|
| rmdas08 | 94.91 | 4.41 | 0.68 |
| rmdas09 | 94.91 | 5.01 | 0.08 |
| rmdas01 | 94.57 | 5.35 | 0.08 |
| rmdas10 | 94.31 | 5.35 | 0.34 |
| rmdas06 | 84.55 | 15.45 | 0.00 |
| rmdas07 | 84.21 | 15.11 | 0.68 |
| rmdas02 | 76.40 | 23.01 | 0.59 |
| rmdas05 | 58.74 | 41.26 | 0.00 |
| rmdas03 | 51.19 | 48.13 | 0.68 |
| rmdas04 | 29.20 | 70.37 | 0.42 |
Item correlations
| rmdas01 | rmdas02 | rmdas03 | rmdas04 | rmdas05 | rmdas06 | rmdas07 | rmdas08 | rmdas09 | rmdas10 | |
|---|---|---|---|---|---|---|---|---|---|---|
| rmdas01 | NA | 0.26 | 0.15 | 0.10 | 0.25 | 0.36 | 0.20 | 0.12 | 0.33 | 0.22 |
| rmdas02 | 0.26 | NA | 0.38 | 0.19 | 0.37 | 0.44 | 0.18 | 0.12 | 0.19 | 0.11 |
| rmdas03 | 0.15 | 0.38 | NA | 0.27 | 0.34 | 0.27 | 0.10 | 0.08 | 0.12 | 0.09 |
| rmdas04 | 0.10 | 0.19 | 0.27 | NA | 0.32 | 0.16 | 0.13 | 0.09 | 0.05 | 0.06 |
| rmdas05 | 0.25 | 0.37 | 0.34 | 0.32 | NA | 0.42 | 0.26 | 0.16 | 0.17 | 0.08 |
| rmdas06 | 0.36 | 0.44 | 0.27 | 0.16 | 0.42 | NA | 0.37 | 0.36 | 0.27 | 0.14 |
| rmdas07 | 0.20 | 0.18 | 0.10 | 0.13 | 0.26 | 0.37 | NA | 0.24 | 0.08 | 0.08 |
| rmdas08 | 0.12 | 0.12 | 0.08 | 0.09 | 0.16 | 0.36 | 0.24 | NA | 0.09 | 0.08 |
| rmdas09 | 0.33 | 0.19 | 0.12 | 0.05 | 0.17 | 0.27 | 0.08 | 0.09 | NA | 0.14 |
| rmdas10 | 0.22 | 0.11 | 0.09 | 0.06 | 0.08 | 0.14 | 0.08 | 0.08 | 0.14 | NA |
Item - total score correlation
Correlation between the item and the sum of the dichotomous items.
| total score | |
|---|---|
| rmdas01 | 0.47 |
| rmdas02 | 0.65 |
| rmdas03 | 0.62 |
| rmdas04 | 0.52 |
| rmdas05 | 0.71 |
| rmdas06 | 0.69 |
| rmdas07 | 0.49 |
| rmdas08 | 0.36 |
| rmdas09 | 0.36 |
| rmdas10 | 0.29 |
Cronbach’s alpha
##
## Reliability analysis
## Call: psych::alpha(x = .)
##
## raw_alpha std.alpha G6(smc) average_r S/N ase mean sd
## 0.71 0.71 0.72 0.2 2.5 0.012 0.24 0.19
##
## lower alpha upper 95% confidence boundaries
## 0.69 0.71 0.73
##
## Reliability if an item is dropped:
## raw_alpha std.alpha G6(smc) average_r S/N alpha se
## rmdas01 0.69 0.68 0.68 0.19 2.2 0.012
## rmdas02 0.66 0.67 0.67 0.19 2.1 0.014
## rmdas03 0.68 0.69 0.69 0.20 2.2 0.013
## rmdas04 0.70 0.70 0.71 0.21 2.4 0.012
## rmdas05 0.65 0.67 0.67 0.18 2.0 0.014
## rmdas06 0.65 0.65 0.65 0.17 1.9 0.014
## rmdas07 0.69 0.70 0.70 0.20 2.3 0.012
## rmdas08 0.70 0.71 0.71 0.21 2.4 0.012
## rmdas09 0.70 0.70 0.70 0.21 2.4 0.012
## rmdas10 0.71 0.72 0.72 0.22 2.5 0.012
##
## Item statistics
## n raw.r std.r r.cor r.drop mean sd
## rmdas01 1177 0.49 0.56 0.49 0.38 0.054 0.23
## rmdas02 1171 0.65 0.61 0.56 0.50 0.231 0.42
## rmdas03 1170 0.62 0.53 0.45 0.41 0.485 0.50
## rmdas04 1173 0.52 0.45 0.34 0.31 0.707 0.46
## rmdas05 1178 0.70 0.64 0.60 0.54 0.413 0.49
## rmdas06 1178 0.70 0.71 0.71 0.57 0.154 0.36
## rmdas07 1170 0.49 0.50 0.40 0.32 0.152 0.36
## rmdas08 1170 0.36 0.44 0.33 0.26 0.044 0.21
## rmdas09 1177 0.38 0.46 0.35 0.27 0.050 0.22
## rmdas10 1174 0.29 0.38 0.24 0.18 0.054 0.23
##
## Non missing response frequency for each item
## 0 1 miss
## rmdas01 0.95 0.05 0.00
## rmdas02 0.77 0.23 0.01
## rmdas03 0.52 0.48 0.01
## rmdas04 0.29 0.71 0.00
## rmdas05 0.59 0.41 0.00
## rmdas06 0.85 0.15 0.00
## rmdas07 0.85 0.15 0.01
## rmdas08 0.96 0.04 0.01
## rmdas09 0.95 0.05 0.00
## rmdas10 0.95 0.05 0.00Summary tables/statistics for CAM-S (N=1178)
Original item category frequencies (%)
| Item | 0 | 1 | 2 | Missing |
|---|---|---|---|---|
| rcamlf4v | 99.83 | 0.17 | 0.00 | 0.00 |
| rcamlf8d | 97.45 | 2.29 | 0.25 | 0.00 |
| rcamlf8a | 97.28 | 2.38 | 0.34 | 0.00 |
| rcamlf4l | 96.60 | 3.40 | 0.00 | 0.00 |
| rcamlf7a | 85.82 | 12.14 | 1.36 | 0.68 |
| rcamlf3a | 84.47 | 12.14 | 3.40 | 0.00 |
| rcamlf5a | 76.40 | 15.87 | 7.13 | 0.59 |
| rcamlf1a | 74.19 | 25.04 | 0.00 | 0.76 |
| rcamlf6a | 72.58 | 22.75 | 3.99 | 0.68 |
| rcamlf2a | 42.02 | 44.23 | 13.58 | 0.17 |
| rcamlf9a | 25.04 | 68.85 | 5.69 | 0.42 |
Dichotomized item category frequency (%)
| Item | 0 | 1 | Missing |
|---|---|---|---|
| rcamlf4v | 99.83 | 0.17 | 0.00 |
| rcamlf8d | 97.45 | 2.55 | 0.00 |
| rcamlf8a | 97.28 | 2.72 | 0.00 |
| rcamlf4l | 96.60 | 3.40 | 0.00 |
| rcamlf9a | 93.89 | 5.69 | 0.42 |
| rcamlf7a | 85.82 | 13.50 | 0.68 |
| rcamlf3a | 84.47 | 15.53 | 0.00 |
| rcamlf5a | 76.40 | 23.01 | 0.59 |
| rcamlf1a | 74.19 | 25.04 | 0.76 |
| rcamlf6a | 72.58 | 26.74 | 0.68 |
| rcamlf2a | 42.02 | 57.81 | 0.17 |
Item correlations
| rcamlf1a | rcamlf2a | rcamlf3a | rcamlf4l | rcamlf4v | rcamlf5a | rcamlf6a | rcamlf7a | rcamlf8a | rcamlf8d | rcamlf9a | |
|---|---|---|---|---|---|---|---|---|---|---|---|
| rcamlf1a | NA | 0.33 | 0.52 | 0.25 | 0.07 | 0.35 | 0.27 | 0.67 | 0.17 | 0.09 | 0.13 |
| rcamlf2a | 0.33 | NA | 0.33 | 0.15 | 0.04 | 0.35 | 0.37 | 0.22 | 0.11 | 0.08 | 0.06 |
| rcamlf3a | 0.52 | 0.33 | NA | 0.22 | 0.04 | 0.44 | 0.38 | 0.38 | 0.25 | 0.12 | 0.16 |
| rcamlf4l | 0.25 | 0.15 | 0.22 | NA | -0.01 | 0.16 | 0.17 | 0.17 | 0.08 | 0.18 | 0.31 |
| rcamlf4v | 0.07 | 0.04 | 0.04 | -0.01 | NA | 0.03 | 0.07 | 0.10 | 0.25 | -0.01 | -0.01 |
| rcamlf5a | 0.35 | 0.35 | 0.44 | 0.16 | 0.03 | NA | 0.43 | 0.23 | 0.13 | 0.14 | 0.09 |
| rcamlf6a | 0.27 | 0.37 | 0.38 | 0.17 | 0.07 | 0.43 | NA | 0.18 | 0.16 | 0.08 | 0.10 |
| rcamlf7a | 0.67 | 0.22 | 0.38 | 0.17 | 0.10 | 0.23 | 0.18 | NA | 0.10 | 0.00 | 0.09 |
| rcamlf8a | 0.17 | 0.11 | 0.25 | 0.08 | 0.25 | 0.13 | 0.16 | 0.10 | NA | 0.04 | 0.03 |
| rcamlf8d | 0.09 | 0.08 | 0.12 | 0.18 | -0.01 | 0.14 | 0.08 | 0.00 | 0.04 | NA | 0.10 |
| rcamlf9a | 0.13 | 0.06 | 0.16 | 0.31 | -0.01 | 0.09 | 0.10 | 0.09 | 0.03 | 0.10 | NA |
Item - total score correlation
Correlation between the item and the sum of the dichotomous items.
| total score | |
|---|---|
| rcamlf1a | 0.74 |
| rcamlf2a | 0.64 |
| rcamlf3a | 0.72 |
| rcamlf4l | 0.39 |
| rcamlf4v | 0.11 |
| rcamlf5a | 0.67 |
| rcamlf6a | 0.65 |
| rcamlf7a | 0.60 |
| rcamlf8a | 0.30 |
| rcamlf8d | 0.23 |
| rcamlf9a | 0.30 |
Cronbach’s alpha
##
## Reliability analysis
## Call: psych::alpha(x = .)
##
## raw_alpha std.alpha G6(smc) average_r S/N ase mean sd
## 0.73 0.71 0.73 0.18 2.4 0.0098 0.16 0.17
##
## lower alpha upper 95% confidence boundaries
## 0.72 0.73 0.75
##
## Reliability if an item is dropped:
## raw_alpha std.alpha G6(smc) average_r S/N alpha se
## rcamlf1a 0.68 0.65 0.66 0.16 1.8 0.0120
## rcamlf2a 0.71 0.68 0.71 0.17 2.1 0.0106
## rcamlf3a 0.68 0.65 0.68 0.16 1.9 0.0118
## rcamlf4l 0.73 0.69 0.72 0.18 2.2 0.0101
## rcamlf4v 0.74 0.72 0.74 0.21 2.6 0.0099
## rcamlf5a 0.69 0.67 0.69 0.17 2.0 0.0113
## rcamlf6a 0.70 0.67 0.70 0.17 2.1 0.0108
## rcamlf7a 0.70 0.67 0.69 0.17 2.1 0.0107
## rcamlf8a 0.73 0.70 0.72 0.19 2.4 0.0100
## rcamlf8d 0.74 0.72 0.74 0.20 2.5 0.0098
## rcamlf9a 0.74 0.71 0.73 0.20 2.4 0.0097
##
## Item statistics
## n raw.r std.r r.cor r.drop mean sd
## rcamlf1a 1169 0.74 0.69 0.72 0.604 0.2524 0.435
## rcamlf2a 1176 0.64 0.55 0.48 0.445 0.5791 0.494
## rcamlf3a 1178 0.72 0.69 0.68 0.606 0.1553 0.362
## rcamlf4l 1178 0.40 0.48 0.38 0.309 0.0340 0.181
## rcamlf4v 1178 0.11 0.28 0.14 0.093 0.0017 0.041
## rcamlf5a 1171 0.67 0.60 0.56 0.512 0.2314 0.422
## rcamlf6a 1170 0.64 0.57 0.52 0.466 0.2692 0.444
## rcamlf7a 1170 0.60 0.56 0.55 0.456 0.1359 0.343
## rcamlf8a 1178 0.31 0.41 0.30 0.219 0.0272 0.163
## rcamlf8d 1178 0.24 0.33 0.19 0.150 0.0255 0.158
## rcamlf9a 1173 0.30 0.37 0.24 0.180 0.0571 0.232
##
## Non missing response frequency for each item
## 0 1 miss
## rcamlf1a 0.75 0.25 0.01
## rcamlf2a 0.42 0.58 0.00
## rcamlf3a 0.84 0.16 0.00
## rcamlf4l 0.97 0.03 0.00
## rcamlf4v 1.00 0.00 0.00
## rcamlf5a 0.77 0.23 0.01
## rcamlf6a 0.73 0.27 0.01
## rcamlf7a 0.86 0.14 0.01
## rcamlf8a 0.97 0.03 0.00
## rcamlf8d 0.97 0.03 0.00
## rcamlf9a 0.94 0.06 0.00##
## Running model: cfa-drs-1-1-2pl.inp
## System command: cd "." && "/Applications/Mplus/mplus" "cfa-drs-1-1-2pl.inp"
## Reading model: cfa-drs-1-1-2pl.out
##
## Running model: cfa-drs-2-1-2pl.inp
## System command: cd "." && "/Applications/Mplus/mplus" "cfa-drs-2-1-2pl.inp"
## Reading model: cfa-drs-2-1-2pl.out##
## Running model: cfa-drs-1-1-wlsmv.inp
## System command: cd "." && "/Applications/Mplus/mplus" "cfa-drs-1-1-wlsmv.inp"
## Reading model: cfa-drs-1-1-wlsmv.out
##
## Running model: cfa-drs-2-1-wlsmv.inp
## System command: cd "." && "/Applications/Mplus/mplus" "cfa-drs-2-1-wlsmv.inp"
## Reading model: cfa-drs-2-1-wlsmv.out##
## Running model: cfa-mdas-1-1-2pl.inp
## System command: cd "." && "/Applications/Mplus/mplus" "cfa-mdas-1-1-2pl.inp"
## Reading model: cfa-mdas-1-1-2pl.out
##
## Running model: cfa-mdas-2-1-2pl.inp
## System command: cd "." && "/Applications/Mplus/mplus" "cfa-mdas-2-1-2pl.inp"
## Reading model: cfa-mdas-2-1-2pl.out##
## Running model: cfa-mdas-1-1-wlsmv.inp
## System command: cd "." && "/Applications/Mplus/mplus" "cfa-mdas-1-1-wlsmv.inp"
## Reading model: cfa-mdas-1-1-wlsmv.out
##
## Running model: cfa-mdas-2-1-wlsmv.inp
## System command: cd "." && "/Applications/Mplus/mplus" "cfa-mdas-2-1-wlsmv.inp"
## Reading model: cfa-mdas-2-1-wlsmv.out##
## Running model: cfa-cam-1-1-2pl.inp
## System command: cd "." && "/Applications/Mplus/mplus" "cfa-cam-1-1-2pl.inp"
## Reading model: cfa-cam-1-1-2pl.out
##
## Running model: cfa-cam-2-1-2pl.inp
## System command: cd "." && "/Applications/Mplus/mplus" "cfa-cam-2-1-2pl.inp"
## Reading model: cfa-cam-2-1-2pl.out##
## Running model: cfa-cam-1-1-wlsmv.inp
## System command: cd "." && "/Applications/Mplus/mplus" "cfa-cam-1-1-wlsmv.inp"
## Reading model: cfa-cam-1-1-wlsmv.out
##
## Running model: cfa-cam-2-1-wlsmv.inp
## System command: cd "." && "/Applications/Mplus/mplus" "cfa-cam-2-1-wlsmv.inp"
## Reading model: cfa-cam-2-1-wlsmv.outModel Fitting (Dichotomous model)
Fit CFA models
We will fit a CFA in the MDAS, DRS, and CAM-S individually then equate them. To ensure that the CFA covers the same dimension for each test, we are fitting the CFA to a core set of items in common across test and then add in the remaining items keeping the core item parameters fixed.
The core set of items are:
| Feature | DRS | MDAS | CAM-S |
|---|---|---|---|
| Sleep disturbance | drs01 | mdas10 | camlf9a |
| Perceptual disturbance | drs02 | mdas07 | camlf7a |
| Psychomotor agitation/retardation | drs07, drs08 | mdas09 | camlf8a, camlf8d |
| Orientation | drs09 | mdas02 | camlf5a |
| Attention | drs10 | mdas04, mdas05 | camlf2a |
| Memory impairment | drs11, drs12 | mdas03 | camlf6a |
| Disorganized thinking/thought process abnormalities | drs06 | mdas06 | camlf3a |
NOTE: In the original 2PL models, the sleep item did not fit well. To try to improve the fit, we tried changing to a 3PL model. This did not improve the fit. So, next we changed the way we dichotomized sleep. Instead of grouping the categories 0 vs 1, 2, 3, we used 0, 1 vs 2, 3. This helped improve the fit in the DRS and MDAS a lot and in the CAM-S a little.
DRS Confirmatory Factor Analysis
Fit statistics
Model 1| N | CFI | RMSEA |
|---|---|---|
| 1178 | 0.98 | 0.03 |
| N | CFI | RMSEA |
|---|---|---|
| 1178 | 0.97 | 0.08 |
Item Parameters
Model 1| Item | Slope | Threshold |
|---|---|---|
| rdrs06 | 3.54 | 4.31 |
| rdrs10 | 2.66 | -0.55 |
| rdrs09 | 1.75 | 1.68 |
| rdrs07 | 1.63 | 4.69 |
| rdrs11 | 1.36 | 0.13 |
| rdrs02 | 1.20 | 2.14 |
| rdrs08 | 1.09 | 4.26 |
| rdrs01 | 0.93 | 3.04 |
| Item | Slope | Threshold |
|---|---|---|
| rdrs06 | 3.54 | 4.31 |
| rdrs10 | 2.66 | -0.55 |
| rdrs12 | 2.44 | -0.31 |
| rdrs09 | 1.75 | 1.68 |
| rdrs07 | 1.63 | 4.69 |
| rdrs13 | 1.61 | 2.75 |
| rdrs05 | 1.59 | 2.67 |
| rdrs03 | 1.51 | 4.02 |
| rdrs04 | 1.49 | 4.75 |
| rdrs11 | 1.36 | 0.13 |
| rdrs02 | 1.20 | 2.14 |
| rdrs08 | 1.09 | 4.26 |
| rdrs01 | 0.93 | 3.04 |
The McDonald’s omega statistic for the DRS is 0.91.
MDAS Confirmatory Factor Analysis
Fit statistics
Model 1| N | CFI | RMSEA |
|---|---|---|
| 1178 | 0.97 | 0.04 |
| N | CFI | RMSEA |
|---|---|---|
| 1178 | 0.98 | 0.02 |
Item Parameters
Model 1| Item | Slope | Threshold |
|---|---|---|
| rmdas06 | 3.77 | 4.23 |
| rmdas05 | 2.55 | 0.69 |
| rmdas02 | 2.12 | 1.99 |
| rmdas03 | 1.45 | 0.08 |
| rmdas09 | 1.42 | 3.76 |
| rmdas07 | 1.20 | 2.14 |
| rmdas04 | 1.20 | -1.12 |
| rmdas10 | 0.80 | 3.14 |
| Item | Slope | Threshold |
|---|---|---|
| rmdas06 | 3.77 | 4.23 |
| rmdas05 | 2.55 | 0.69 |
| rmdas01 | 2.51 | 4.97 |
| rmdas02 | 2.12 | 1.99 |
| rmdas08 | 1.59 | 4.06 |
| rmdas03 | 1.45 | 0.08 |
| rmdas09 | 1.42 | 3.76 |
| rmdas07 | 1.20 | 2.14 |
| rmdas04 | 1.20 | -1.12 |
| rmdas10 | 0.80 | 3.14 |
The McDonald’s omega statistic for the MDAS is 0.89.
CAM-S Confirmatory Factor Analysis
Fit statistics
Model 1| N | CFI | RMSEA |
|---|---|---|
| 1178 | 0.99 | 0.02 |
| N | CFI | RMSEA |
|---|---|---|
| 1178 | 0.9 | 0.1 |
Item Parameters
Model 1| Item | Slope | Threshold |
|---|---|---|
| rcamlf3a | 3.92 | 4.37 |
| rcamlf2a | 2.45 | -0.60 |
| rcamlf5a | 2.27 | 2.09 |
| rcamlf6a | 1.96 | 1.59 |
| rcamlf8a | 1.65 | 4.74 |
| rcamlf7a | 1.36 | 2.40 |
| rcamlf8d | 1.01 | 4.11 |
| rcamlf9a | 0.73 | 3.03 |
| Item | Slope | Threshold |
|---|---|---|
| rcamlf3a | 3.92 | 4.37 |
| rcamlf1a | 2.61 | 2.08 |
| rcamlf2a | 2.45 | -0.60 |
| rcamlf5a | 2.27 | 2.09 |
| rcamlf4v | 2.07 | 8.41 |
| rcamlf6a | 1.96 | 1.59 |
| rcamlf4l | 1.87 | 4.75 |
| rcamlf8a | 1.65 | 4.74 |
| rcamlf7a | 1.36 | 2.40 |
| rcamlf8d | 1.01 | 4.11 |
| rcamlf9a | 0.73 | 3.03 |
The McDonald’s omega statistic for the CAM-S is 0.91.
Item equating
Using the SNSequate package to equate item parameters.
DRS item parameters
| Item | A | B1 |
|---|---|---|
| rdrs01 | 0.93 | 3.26 |
| rdrs02 | 1.20 | 1.78 |
| rdrs03 | 1.51 | 2.66 |
| rdrs04 | 1.49 | 3.20 |
| rdrs05 | 1.59 | 1.68 |
| rdrs06 | 3.54 | 1.22 |
| rdrs07 | 1.63 | 2.88 |
| rdrs08 | 1.09 | 3.91 |
| rdrs09 | 1.75 | 0.96 |
| rdrs10 | 2.66 | -0.21 |
| rdrs11 | 1.36 | 0.10 |
| rdrs12 | 2.44 | -0.13 |
| rdrs13 | 1.61 | 1.71 |
MDAS item parameters
| Item | A | B1 |
|---|---|---|
| rmdas01 | 2.51 | 1.98 |
| rmdas02 | 2.12 | 0.94 |
| rmdas03 | 1.45 | 0.05 |
| rmdas04 | 1.20 | -0.94 |
| rmdas05 | 2.55 | 0.27 |
| rmdas06 | 3.77 | 1.12 |
| rmdas07 | 1.20 | 1.78 |
| rmdas08 | 1.59 | 2.55 |
| rmdas09 | 1.42 | 2.64 |
| rmdas10 | 0.80 | 3.95 |
CAM-S item parameters
| Item | A | B1 |
|---|---|---|
| rcamlf1a | 2.61 | 0.80 |
| rcamlf2a | 2.45 | -0.24 |
| rcamlf3a | 3.92 | 1.11 |
| rcamlf4l | 1.87 | 2.54 |
| rcamlf4v | 2.07 | 4.07 |
| rcamlf5a | 2.27 | 0.92 |
| rcamlf6a | 1.96 | 0.81 |
| rcamlf7a | 1.36 | 1.76 |
| rcamlf8a | 1.65 | 2.87 |
| rcamlf8d | 1.01 | 4.07 |
| rcamlf9a | 0.73 | 4.17 |
The items used to link the MDAS to the DRS are: Disorientation, Perceptual disturbance, Sleep/wake cycle disturbance, Short term memory impairment, Delusions, and Thought process abnormality/Disorganized thinking.
The items used to link the CAM-S to the DRS are: Disorientation, Perceptual disturbance, Sleep/wake cycle disturbance, Psychomotor agitation, Psychomotor retardation, Attention, and Thought process abnormality/Disorganized thinking.
##
## Running model: cfa-mdas-link-1.inp
## System command: cd "." && "/Applications/Mplus/mplus" "cfa-mdas-link-1.inp"
## Reading model: cfa-mdas-link-1.outMDAS item parameters linked
| Item | A (original) | B (original) | A (linked) | B (linked) |
|---|---|---|---|---|
| rmdas01 | 2.51 | 1.98 | 2.33 | 2.00 |
| rmdas02 | 2.12 | 0.94 | 1.97 | 0.88 |
| rmdas03 | 1.45 | 0.05 | 1.34 | -0.07 |
| rmdas04 | 1.20 | -0.94 | 1.11 | -1.14 |
| rmdas05 | 2.55 | 0.27 | 2.37 | 0.16 |
| rmdas06 | 3.77 | 1.12 | 3.50 | 1.08 |
| rmdas07 | 1.20 | 1.78 | 1.12 | 1.79 |
| rmdas08 | 1.59 | 2.55 | 1.48 | 2.62 |
| rmdas09 | 1.42 | 2.64 | 1.32 | 2.71 |
| rmdas10 | 0.80 | 3.95 | 0.74 | 4.12 |
##
## Running model: cfa-cam-link-1.inp
## System command: cd "." && "/Applications/Mplus/mplus" "cfa-cam-link-1.inp"
## Reading model: cfa-cam-link-1.outCAM-S item parameters linked
| Item | A (original) | B (original) | A (linked) | B (linked) |
|---|---|---|---|---|
| rcamlf1a | 2.61 | 0.80 | 2.54 | 0.86 |
| rcamlf2a | 2.45 | -0.24 | 2.39 | -0.21 |
| rcamlf3a | 3.92 | 1.11 | 3.82 | 1.18 |
| rcamlf4l | 1.87 | 2.54 | 1.82 | 2.64 |
| rcamlf4v | 2.07 | 4.07 | 2.02 | 4.20 |
| rcamlf5a | 2.27 | 0.92 | 2.22 | 0.98 |
| rcamlf6a | 1.96 | 0.81 | 1.91 | 0.87 |
| rcamlf7a | 1.36 | 1.76 | 1.33 | 1.85 |
| rcamlf8a | 1.65 | 2.87 | 1.61 | 2.98 |
| rcamlf8d | 1.01 | 4.07 | 0.98 | 4.21 |
| rcamlf9a | 0.73 | 4.17 | 0.71 | 4.31 |
Plots for the dichotomous model
## Reading model: cfa-drs-2-1-2pl.out## Reading model: cfa-mdas-link-1.out## Reading model: cfa-cam-link-1.out
Model Fitting (Polytomous model)
DRS CFA model with polytomous outcome
##
## Running model: cfa-drs-3-1.inp
## System command: cd "." && "/Applications/Mplus/mplus" "cfa-drs-3-1.inp"
## Reading model: cfa-drs-3-1.out| Item | A | B1 | B2 | B3 |
|---|---|---|---|---|
| rdrs01 | 0.93 | -1.31 | 3.26 | 6.57 |
| rdrs02 | 1.20 | 1.78 | 2.17 | 2.64 |
| rdrs03 | 1.51 | 2.66 | 3.33 | 3.68 |
| rdrs04 | 1.49 | 3.20 | 4.19 | NA |
| rdrs05 | 1.59 | 1.68 | 3.40 | 4.44 |
| rdrs06 | 3.54 | 1.22 | 1.80 | 2.94 |
| rdrs07 | 1.63 | 2.88 | 4.06 | NA |
| rdrs08 | 1.09 | 3.91 | 5.23 | NA |
| rdrs09 | 1.75 | 0.96 | 1.80 | 3.98 |
| rdrs10 | 2.66 | -0.21 | 1.29 | 3.02 |
| rdrs11 | 1.36 | 0.10 | 1.26 | 1.77 |
| rdrs12 | 2.44 | -0.13 | 0.63 | 1.08 |
| rdrs13 | 1.61 | 1.71 | 3.10 | 5.16 |
MDAS CFA model with polytomous outcome
##
## Running model: cfa-mdas-3-1.inp
## System command: cd "." && "/Applications/Mplus/mplus" "cfa-mdas-3-1.inp"
## Reading model: cfa-mdas-3-1.out| Item | A | B1 | B2 | B3 |
|---|---|---|---|---|
| rmdas01 | 2.33 | 2.00 | 2.97 | NA |
| rmdas02 | 1.97 | 0.88 | 1.75 | 2.53 |
| rmdas03 | 1.34 | -0.07 | 1.02 | 2.59 |
| rmdas04 | 1.11 | -1.14 | 1.97 | 5.14 |
| rmdas05 | 2.37 | 0.16 | 1.41 | 3.14 |
| rmdas06 | 3.50 | 1.08 | 1.89 | 3.07 |
| rmdas07 | 1.12 | 1.79 | 3.82 | 6.85 |
| rmdas08 | 1.48 | 2.62 | 3.61 | 5.44 |
| rmdas09 | 1.32 | 2.71 | 3.93 | NA |
| rmdas10 | 0.74 | -1.71 | 4.12 | 7.99 |
CAM-S CFA model with polytomous outcome
##
## Running model: cfa-cam-3-1.inp
## System command: cd "." && "/Applications/Mplus/mplus" "cfa-cam-3-1.inp"
## Reading model: cfa-cam-3-1.out| Item | A | B1 | B2 |
|---|---|---|---|
| rcamlf1a | 2.54 | 0.86 | NA |
| rcamlf2a | 2.39 | -0.21 | 1.41 |
| rcamlf3a | 3.82 | 1.18 | 2.06 |
| rcamlf4l | 1.82 | 2.64 | NA |
| rcamlf4v | 2.02 | 4.20 | NA |
| rcamlf5a | 2.22 | 0.98 | 1.89 |
| rcamlf6a | 1.91 | 0.87 | 2.43 |
| rcamlf7a | 1.33 | 1.85 | 3.88 |
| rcamlf8a | 1.61 | 2.98 | 4.36 |
| rcamlf8d | 0.98 | 4.21 | 6.61 |
| rcamlf9a | 0.71 | -1.67 | 4.31 |
##
## Running model: cfa-camsf-3-1.inp
## System command: cd "." && "/Applications/Mplus/mplus" "cfa-camsf-3-1.inp"
## Reading model: cfa-camsf-3-1.outPlots for the polytomous model
For the manuscript
This section contains tables/figures for the manuscript.
Table 1
| Variable | N | Mean | SD | Count | Percent |
|---|---|---|---|---|---|
| adlany | 342 | NA | NA | 272 | 79.5 |
| age | 352 | 80.3 | 6.8 | NA | NA |
| dementia | 352 | NA | NA | 101 | 28.7 |
| educ | 344 | 14.5 | 3.0 | NA | NA |
| female | 352 | NA | NA | 207 | 58.8 |
| livesalone | 348 | NA | NA | 133 | 38.2 |
| married | 348 | NA | NA | 139 | 39.9 |
| nonwhite | 352 | NA | NA | 51 | 14.5 |
| surgical | 352 | NA | NA | 102 | 29.0 |
Table 2
Summary of delirium severity instruments from all hospital interviews.| Variable | N | Mean | SD | Min | Median | Max |
|---|---|---|---|---|---|---|
| CAMS.LF | 1178 | 2.3 | 2.4 | 0 | 1 | 14 |
| CAMS.SF | 1178 | 0.7 | 1.3 | 0 | 0 | 6 |
| DRS | 1178 | 4.7 | 4.3 | 0 | 3 | 28 |
| MDAS | 1178 | 3.9 | 3.3 | 0 | 3 | 22 |
Table 3
| Delirium Instrument | CFI | RMSEA |
|---|---|---|
| DRS (Model using only common features) | 0.98 | 0.03 |
| DRS (Model using all features) | 0.97 | 0.08 |
| MDAS (Model using only common features) | 0.97 | 0.04 |
| MDAS (Model using all features) | 0.98 | 0.02 |
| CAM-S (Model using only common features) | 0.99 | 0.02 |
| CAM-S (Model using all features) | 0.90 | 0.10 |
| * CFI = Confirmatory Fit Index, RMSEA = Root Mean Squared Error of Approximation | ||
| † Values indicating good fit are: CFI>.9, RMSEA<.06 |
Figure 1
Figure 2
Figure 3
Figure 4
For the appendix
This section contains tables/figures for the appendix.
Tables of item parameters
Parameters are unstandardized factor loading and thresholds from the final mplus output. Considered adding standard errors to the table, but because in this final model we are estimating the thresholds for the more severe categories, all the other parameters have been constrained to previous estimates, so it would be difficult and may not make sense to include standard errors.
CAM-S long form
| Item | Factor loading | Threshold 1 | Threshold 2 |
|---|---|---|---|
| camlf1a | 2.545 | 2.179 | NA |
| camlf2a | 2.393 | -0.507 | 3.364 |
| camlf3a | 3.823 | 4.510 | 7.884 |
| camlf4l | 1.822 | 4.814 | NA |
| camlf4v | 2.018 | 8.485 | NA |
| camlf5a | 2.218 | 2.171 | 4.201 |
| camlf6a | 1.908 | 1.661 | 4.627 |
| camlf7a | 1.326 | 2.447 | 5.151 |
| camlf8a | 1.608 | 4.796 | 7.016 |
| camlf8d | 0.985 | 4.147 | 6.506 |
| camlf9a | 0.708 | -1.181 | 3.053 |
DRS-R-98
| Item | Factor loading | Threshold 1 | Threshold 2 | Threshold 3 |
|---|---|---|---|---|
| drs01 | 0.934 | -1.228 | 3.044 | 6.133 |
| drs02 | 1.204 | 2.141 | 2.614 | 3.184 |
| drs03 | 1.514 | 4.024 | 5.037 | 5.579 |
| drs04 | 1.485 | 4.750 | 6.217 | NA |
| drs05 | 1.589 | 2.667 | 5.400 | 7.052 |
| drs06 | 3.542 | 4.310 | 6.391 | 10.428 |
| drs07 | 1.629 | 4.687 | 6.607 | NA |
| drs08 | 1.090 | 4.262 | 5.698 | NA |
| drs09 | 1.748 | 1.675 | 3.139 | 6.962 |
| drs10 | 2.665 | -0.550 | 3.431 | 8.041 |
| drs11 | 1.358 | 0.132 | 1.716 | 2.401 |
| drs12 | 2.445 | -0.311 | 1.545 | 2.652 |
| drs13 | 1.607 | 2.754 | 4.974 | 8.292 |
MDAS
| Item | Factor loading | Threshold 1 | Threshold 2 | Threshold 3 |
|---|---|---|---|---|
| mdas01 | 2.332 | 4.667 | 6.921 | NA |
| mdas02 | 1.965 | 1.733 | 3.434 | 4.964 |
| mdas03 | 1.343 | -0.097 | 1.371 | 3.482 |
| mdas04 | 1.110 | -1.269 | 2.192 | 5.707 |
| mdas05 | 2.370 | 0.382 | 3.351 | 7.443 |
| mdas06 | 3.504 | 3.776 | 6.634 | 10.757 |
| mdas07 | 1.116 | 1.997 | 4.261 | 7.645 |
| mdas08 | 1.477 | 3.869 | 5.339 | 8.042 |
| mdas09 | 1.322 | 3.588 | 5.193 | NA |
| mdas10 | 0.738 | -1.265 | 3.042 | 5.899 |
Table A1: Nomogram Crosswalk tables
Table A1a: CAM-S LF table
| CAM-S LF | MDAS | DRS-R-98 | CAM-S SF |
|---|---|---|---|
| 0 | 0.2 | 0.1 | 0.0 |
| 1 | 1.9 | 1.5 | 0.2 |
| 2 | 3.3 | 3.7 | 0.8 |
| 3 | 4.6 | 5.5 | 1.3 |
| 4 | 5.8 | 7.2 | 1.8 |
| 5 | 6.9 | 8.7 | 2.3 |
| 6 | 8.0 | 10.2 | 2.9 |
| 7 | 9.2 | 11.8 | 3.4 |
| 8 | 10.4 | 13.4 | 3.9 |
| 9 | 11.8 | 15.1 | 4.4 |
| 10 | 13.1 | 16.7 | 4.8 |
| 11 | 14.7 | 18.5 | 5.2 |
| 12 | 16.4 | 20.7 | 5.5 |
| 13 | 18.4 | 23.3 | 5.8 |
| 14 | 20.4 | 26.0 | 6.1 |
| 15 | 21.8 | 28.4 | 6.3 |
| 16 | 23.0 | 30.6 | 6.6 |
| 17 | 24.2 | 32.7 | 6.9 |
| 18 | 25.8 | 34.7 | 7.0 |
| 19 | 27.1 | 35.7 | 7.0 |
Table A1b: MDAS table
| MDAS | CAM-S LF | DRS-R-98 | CAM-S SF |
|---|---|---|---|
| 0 | 0.2 | 0.1 | 0.0 |
| 1 | 0.5 | 0.6 | 0.0 |
| 2 | 1.0 | 1.6 | 0.2 |
| 3 | 1.7 | 3.1 | 0.6 |
| 4 | 2.5 | 4.6 | 1.0 |
| 5 | 3.3 | 6.1 | 1.5 |
| 6 | 4.2 | 7.5 | 1.9 |
| 7 | 5.1 | 8.9 | 2.4 |
| 8 | 6.0 | 10.2 | 2.9 |
| 9 | 6.9 | 11.6 | 3.3 |
| 10 | 7.6 | 12.9 | 3.7 |
| 11 | 8.4 | 14.1 | 4.1 |
| 12 | 9.2 | 15.3 | 4.4 |
| 13 | 9.9 | 16.5 | 4.8 |
| 14 | 10.6 | 17.7 | 5.1 |
| 15 | 11.2 | 18.9 | 5.3 |
| 16 | 11.8 | 20.1 | 5.5 |
| 17 | 12.3 | 21.5 | 5.6 |
| 18 | 12.8 | 22.7 | 5.8 |
| 19 | 13.3 | 24.0 | 5.9 |
| 20 | 13.8 | 25.5 | 6.0 |
| 21 | 14.4 | 27.1 | 6.2 |
| 22 | 15.1 | 28.7 | 6.4 |
| 23 | 16.0 | 30.6 | 6.6 |
| 24 | 16.8 | 32.4 | 6.8 |
| 25 | 17.5 | 33.8 | 6.9 |
| 26 | 18.1 | 34.9 | 7.0 |
| 27 | 18.6 | 35.6 | 7.0 |
Table A1c: DRS-R-98 table
| DRS-R-98 | CAM-S LF | MDAS | CAM-S SF |
|---|---|---|---|
| 0 | 0.2 | 0.2 | 0.0 |
| 1 | 0.7 | 1.5 | 0.1 |
| 2 | 1.2 | 2.3 | 0.3 |
| 3 | 1.7 | 2.9 | 0.6 |
| 4 | 2.2 | 3.6 | 0.9 |
| 5 | 2.7 | 4.2 | 1.1 |
| 6 | 3.3 | 4.9 | 1.4 |
| 7 | 3.9 | 5.7 | 1.8 |
| 8 | 4.5 | 6.4 | 2.1 |
| 9 | 5.2 | 7.1 | 2.4 |
| 10 | 5.9 | 7.8 | 2.8 |
| 11 | 6.5 | 8.5 | 3.1 |
| 12 | 7.1 | 9.3 | 3.5 |
| 13 | 7.7 | 10.1 | 3.8 |
| 14 | 8.3 | 10.9 | 4.0 |
| 15 | 9.0 | 11.7 | 4.3 |
| 16 | 9.6 | 12.6 | 4.6 |
| 17 | 10.2 | 13.4 | 4.9 |
| 18 | 10.8 | 14.3 | 5.1 |
| 19 | 11.3 | 15.1 | 5.3 |
| 20 | 11.7 | 15.9 | 5.5 |
| 21 | 12.1 | 16.6 | 5.6 |
| 22 | 12.5 | 17.5 | 5.7 |
| 23 | 12.9 | 18.2 | 5.8 |
| 24 | 13.2 | 18.9 | 5.9 |
| 25 | 13.6 | 19.7 | 6.0 |
| 26 | 14.0 | 20.4 | 6.1 |
| 27 | 14.4 | 21.0 | 6.2 |
| 28 | 14.8 | 21.6 | 6.3 |
| 29 | 15.2 | 22.1 | 6.4 |
| 30 | 15.7 | 22.7 | 6.5 |
| 31 | 16.2 | 23.2 | 6.7 |
| 32 | 16.7 | 23.8 | 6.8 |
| 33 | 17.1 | 24.4 | 6.9 |
| 34 | 17.6 | 25.1 | 7.0 |
| 35 | 18.2 | 26.1 | 7.0 |
| 36 | 18.7 | 27.1 | 7.0 |
Table A1d: CAM-S SF table
| CAM-S SF | MDAS | DRS-R-98 | CAM-S LF |
|---|---|---|---|
| 0 | 0.2 | 0.1 | 0.2 |
| 1 | 3.9 | 4.5 | 2.4 |
| 2 | 6.2 | 7.7 | 4.4 |
| 3 | 8.3 | 10.6 | 6.3 |
| 4 | 10.8 | 13.8 | 8.2 |
| 5 | 13.8 | 17.4 | 10.5 |
| 6 | 19.9 | 25.3 | 13.7 |
| 7 | 27.1 | 35.7 | 18.7 |
Figures A1: Nomogram Crosswalk figures for CAM-S LF
Figure A1a: CAM-S LF nomogram crosswalk crosswalk with MDAS and DRS-R-98
Figure A1b: CAM-S LF nomogram crosswalk with CAM-S SF and DRS-R-98
Figure A1c: CAM-S LF nomogram crosswalk with CAM-S SF and MDAS
Figure A2: Nomogram Crosswalk figures for MDAS
Figure A2a: MDAS nomogram crosswalk with CAM-S LF and DRS-R-98
Figure A2b: MDAS nomogram crosswalk with CAM-S SF and DRS-R-98
Figure A2c: MDAS nomogram crosswalk with CAM-S SF and CAM-S LF
Figure A3: Nomogram Crosswalk figures for DRS-R-98
Figure A3a: DRS-R-98 nomogram crosswalk with MDAS and CAM-S LF
Figure A3b: DRS-R-98 nomogram crosswalk with MDAS and CAM-S SF
Figure A3c: DRS-R-98 nomogram crosswalk with CAM-S LF and CAM-S SF
Figure A4: Nomogram Crosswalk figures for CAM-S SF
Figure A4a: CAM-S SF nomogram crosswalk with MDAS and DRS-R-98
Figure A4b: CAM-S SF nomogram crosswalk with MDAS and CAM-S LF
Figure A4c: CAM-S SF nomogram crosswalk with DRS-R-98 and CAM-S LF
Sensitivity/Supplemental Analyses
This section contains analyses that are more exploratory in nature, and could be supplemental to the manuscript.
Information plots using only first threshold
These analyses explore the contribution the second and third thresholds have on the overall information levels of the instruments.
Figure S1: Test Information Curve using only the first threshold
Figure S2: Difference in Information curves between dichotomous and polytomous outcomes
Figure S3: Difference in measurement error between dichotomous and polytomous outcomes
Figure S4: Boxplot of standard error of measurement for dichotomous model (from Mplus)
The delirium intensity has been cut into bins of size = 0.2. Boxplots of the SEM are shown for each bin.
Figure S5: Boxplot of standard error of measurement for polytomous model (from Mplus)
The delirium intensity has been cut into bins of size = 0.2. Boxplots of the SEM are shown for each bin. 
Figure S6: Standard error of measurement for dichotomous model (from Information function)
Figure S7: Standard error of measurement for polytomous model (from Information function)
